Switch interlock structure



Oct. 5, 1965 D. DANlELs 3,209,634

SWITCH INTERLOCK STRUCTURE Filed Nov. 2, 1962 A TTORNE YS United States Patent 3,209,634 SWITCH INTERLOCK STRUCTURE Dennis Daniels, Williamsville, N .Y., assignor to Houdaille Industries, Inc., a corporation nf Michigan Filed Nov. 2, 1962, Ser. No. 235,048 6 Claims. (Cl. 83-399) This invention relates generally to switch actuating structures, and more specifically to a switch interlock structure adapted to be responsive to two separate mechanical means.

Although the principles of the present invention may be included in various devices, a particularly useful application is made in a machine tool of the punch'press type which is adapted to be employed with tooling which is readily manually replaceable and interchangeable, such as between successive strokes thereof. In particular, when such interchangeable tooling is to be employed, it must be held in place by readily releasable means, such as manual clamps. There is a possibility that an operator in replacing one clamped tool, such as a punch, may fail to clamp the tool completely, whereupon the subsequent stroke of the press ram causes the punch to strike the edge of the die, severely damaging one or both of the tools. It has been previously proposed to provide a switch interlock structure for each such clamp.

The present invention contemplates the utilization of a single switch provided with novel support and actuating means responsive to two separate spaced manually actuable clamps, the switch being adapted to be connected in the actuating circuit of the punching device and to prevent operation of the punching device at any time that either one of the clamps is not fully closed, seated, or clamped.

Accordingly, it is an object of the present invention to provide an improved switch interlock structure.

Another object of the present invention is to provide a switch interlock structure for a machine tool, which interlock structure is characterized by its extreme simplicity.

Yet another object of the present invention is to provide a switch interlock structure which may be adjusted after installation to compensate for all variables.

Many other features, advantages and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying drawing sheet in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.

On the drawing:

The figure is an elevational view, partly in cross-section, of a switch interlock structure provided in accordance with the principles of the present invention, the same being illustrated in an installed position in a fra-gmentarily illustrated and cross-sectioned portion of a representative machine tool.

As shown on the drawing:

The principles of this invention are particularly useful when embodied in a switch interlock structure such as illustrated in the drawing, generally indicated by the numeral 10. The interlock structure includes a single electric switch 11 supported by a support member 12, the switch 11 having an actuator 13 of the plunger type ICC engaged by an operating member generally indicated at 14.

The switch 11 preferably is of the snap-acting type and is so constructed that the plunger or actuator 13 has some overtravel in its inner or actuated position.

The support member 12 includes a sheet metal U- shaped bracket 15 to which the switch 11 is secured as by a pair of nut and bolt assemblies 16. A threaded boss 17 is secured to the bracket 15 such as by weldingT and forms part of a connection with a iirst rod 18 which has threads 19 at one end thereof received in the boss 17. The connection preferably further includes a jam nut 20 and washer 21. The other end of the rod 18 is slotted and is externally accessible for rotation during adjustment or setting of the effective adjustable length of the support member 12.

The operating member 14 includes an internally threaded head 22 which abuts the switch actuator 13 and which receives a threaded end of a second rod 23. A further jam nut 2t) and washer 21 lock the effective adjustable length of the operating member 14, the outer end of which is similarly bifurcated to facilitate such adjustment.

The head 22 is provided with a ange 24. A spring 25 of the compression type surrounds the actuator 13 and the head 22 and acts between the ange 24 and the case of the switch 11 to urge the head 22 away from the actuator 13. It is to be understood that if the spring (not shown) normally provided in the switch 11 is sufticiently strong to insure sliding of the rods 18 and 23, the spring 25 may be omitted.

The switch 11 is provided with a pair of terminals 26 by which the switch is adapted to be connected serially in the actuating circuit of the device which is to be protected.

When the actuator 13 is in the inner or actuated position, the over-all length across the outer ends of the rods 1S and 23 is of a predetermined value. It is to be understood that only one such adjustable-length connection need be provided to adjust the over-all length of the interlock mechanism. However, as brought out below, it is preferable that separate adjustments be provided for each of the rods 13 and 23.

The switch interlock mechanism 10 may be employed with and as a part of a machine tool, a portion of which is generally indicated at 27, for example a device of the punching machine type, which includes a frame 28 provided with a pair of spaced clamps 29, 30, respectively having handles 31 and 32 for operating the same. Each of the handles 31 and 32 is pivoted about an axis 33 which effects disengagement of a hook 34, thereby releasing tooling, supports for such tooling being illustrated at 35, 35.

A more detailed description of the clamp means 29, 30 is shown and claimed in the copending application of A. K. Schott et al. for U.S. Patent on a Punching Machine `and Structure therefor, filed November 1, 1960, U.S. Serial No. 66,639.

The clamp means 29 are illustrated in the fully clamped position, and the handle 31 thereof can pivot in a clockwise direction to release the tooling indicated at 35. Similarly, -the handle 32 may be pivoted in a counterclockwise direction to release the tooling 35 held by the clamp 30. As illustrated, the handles 31 and 32 of the clamps 29 and 30 are shown in their innermost or clamped position,

wherein the clamps 29 and 30 respectively engage the bifurcated ends of the rods 18 and 23. When either of these clamps is moved out of the illustrated fully clamped position, the actuator 13 will move away from the bracket 15 supporting the switch 11, thereby operating the switch. If the switch is normally closed to enable machine tool operation, such movement opens the switch 11. Opening such switch opens the actuating circuit of the electrically actuated punching machine Z7'.

For purposes of protection, it is preferable that the frame 28 be provided with a cavity 36 within which the supported switch 11 is disposed, there being a pair of passages 37, 38 leading therefrom to the clamps 29, 30. The rods 18 and 23 are slidably received and supported in the passages 37, 38. By this structure, the switch 11 is rendered responsive to the position of both of the clamps 29, 30.

The adjustable length connections are so adjusted that when both of the rods 18 and 23 are in their respective inner positions, as illustrated, there will be a gap in the cavity 36 between an end wall thereof and each of the jam nuts 20. These gaps are indicated at 39 and 40. The gap 39 is sufficiently large to enable the switch 11 to move to the left in response to partial opening of the clamp 29, such movement to the left being sufficient to actuate the switch. Similarly, the gap 40 is sufficiently large to enable the actuator member 14 to move to the right in response to partial opening of the clamp 30, such movement also being suiiicient to actuate the switch. When both clamps are open, the spring 25 may urge the nuts 20 against the walls of the cavity 36, thereby causing each of the rods to project respectively into the paths of the clamping mechanisms 29 and 30. Thus, upon full reclosing of one of the clamps, the associated rod 18 or 23 will move to the inner illustrated position, the magnitude of such movement being insufficient to actuate the switch 11. However, upon the other rods being similarly moved to the illustrated inner position, the switch 11 is actuated, thereby enabling and permitting the electrical actuating circuit to be operated.

Within limits, a single adjustment may be elfected t coordinate the interlock mechanism with two separate clamps, and the interlock mechanism thus includes only one switch.

Although various minor modications might be suggested by those versed in the art, it should be understood that I Wish to embody within the scope of the patent warranted hereon all such embodiments as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. In an electrically actuated punching machine having interchangeable tooling held in operating position on a frame by a pair `of individually and independently actuatable spaced clamps, the improvement comprising: a single electrical switch adapted to be connected serially in the actuating circuit of the machine, and responsive to the positions of both of the independently actuatable clamps to render the actuating circuit operative only when both of said clamps are in fully clamped positions, and responsive to a non-fully clamped position of a single one of said clamps to render the actuating circuit inoperative.

2. In an electrically actuated punching machine having interchangeable tooling held in operating position on a frame by a pair of spaced clamps, the improvement comprising:

(a) an electrical switch having an actuator and adapted to be connected serially in the actuating circuit of the machine;

(b) a member supporting said switch and slidably carried by the frame, said supporting member being engageable by one of the clamps and being movable to an inner position in response to said one clamps being in a fully clamped position;

(c) a member adapted to operate the actuator of said switch and carried slidably by the frame, said operating member being engageable by the other of the clamps and being movable to an inner position in response to said other clamps being in a fully clamped position; and

(d) said switch being adapted to render the actuating circuit operative only when both of said members are in their inner positions.

3. In an electrically actuated punching machine having interchangeable tooling held in operating position on a frame by a pair of spaced clamps, the improvement comprising:

(a) an electrical switch having an actuator and adapted to be connected serially in the actuating circuit of the machine;

(b) a member supporting said switch and slidably carried by the frame, said supporti-ng member being engageable by one of the clamps and being movable to an inner position in response to said one clamps being in a fully clamped position;

(c) a member adapted to operate the actuator of said switch and carried slidably by the frame, said operating member being engageable by the other of the clamps and being movable to an inner position in response to said other clamps being in a fully clamped position;

(d) a spring biasing said members toward the respective clamps; and

(e) said switch being adapted to render the actuating circuit operative only when both of said members are in their inner positions.

4. In an electrically actuated punching machine having interchangeable tooling held in operating position on a frame by a pair of spaced clamps, the improvement comprising:

(a) an electrical switch having an actuator and adapted to be connected serially in the actuating circuit of the machine;

(b) a bracket supporting said switch;

(c) a rst rod slidably carried by the frame and having at one end a threaded connection of adjustable length With said bracket, and being engageable at the other end by one of the clamps;

(d) a head engageable with the switch actuator;

(e) a second rod slidably carried by the frame and having at one end a threaded connection of adjustable length with said head, and being engageable at the other end by the other of the clamps; and

(f) said switch being adapted to render the actuating circuit operative only when both of the clamps are in fully clamped positions.

5. In an electrically actuated punching machine having interchangeable tooling held in operating position on a frame by a pair of spaced clamps, the improvement comprising:

(a) an electrical switch having an actuator and adapted to be connected serially in the actuating circuit of the machine;

(b) a bracket supporting said switch;

(c) a first rod slidably carried by the frame and having at one end a threaded connection of adjustable length with said bracket, and being engageable at the other end by one of the clamps;

(d) a head engageable with the switch actuator;

(e) a second rod slidably carried by the frame and having at one end a threaded connection of adjustable length with said head, and being engageable at the other end by the other of the clamps;

(f) a compression spring acting between said switch and said head and biasing said head in a direction away from the switch actuator; and

(g) said switch being adapted to render the actuating circuit operative only when both of the clamps are in fully clamped positions.

6. In an electrically actuated punching machine having interchangeable tooling held in operating position on a frame by a pair of spaced clamps, the improvement comprising:

(a) an electrical switch having an actuator and adapted to be connected serially in the actuating circuit of the machine;

(b) a bracket supporting said switch;

(c) a first rod slidably carried by the frame and having at one end a connection with said bracket, and being engageable at the other end by one of said clamps;

(d) a head engageable with the switch actuator;

(e) a second yrod slidably carried by the frame and having at one end a connection with said head, and being engageable at the other end by the other of the clamps;

(f) one of said connections being threaded and of adjustable length for varying the operating point of said switch; and

(g) said switch being adapted to render the actuating circuit operative only when both of the clamps are in fully clamped positions.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES I.B.M. Technical Disclosure Bulletin Lock for punch and die uni by F. R. Anderholm et al. vol. 3, No. 12,

15 May 1961.

ANDREW R. JUHASZ, Primary` Examiner. HUNTER C. BOURNE, JR., Examiner. 

1. IN AN ELECTRICALLY ACTUATED PUNCHING MACHINE HAVING INTERCHANGEABLE TOOLING HELD IN OPERATING POSITION ON A FRAME BY A PAIR OF INDIVIDUALLY AND INDEPENDENTLY ACTUATABLE SPACED CLAMPS, THE IMPROVEMENT COMPRISING: A SINGLE ELECTRICAL SWITCH ADAPTED TO BE CONNECTED SERIALLY IN THE ACTUATING CIRCUIT OF THE MACHINE, AND RESPONSIVE TO THE POSITIONS OF BOTH OF THE INDEPENDENTLY ACTUATABLE CLAMPS TO RENDER THE ACTUATING CIRCUIT OPERATIVE ONLY WHEN BOTH OF SAID CLAMPS ARE IN FULLY CLAMPED POSITIONS, AND RESPONSIVE TO A NON-FULLY CLAMPED POSITION OF A SINGLE ONE OF SAID CLAMPS TO RENDER THE ACTUATING CIRCUIT INOPERATIVE. 